Answer: About (50-90) full length hair strands should be collected from the scalp to use as a sample.
Hair is a potent physical evidence, used to proof the culprit of crime. The hair analysis goes with preliminary and confirmatory analysis in forensic lab. This requires ample of sample should be available for analysis and comparison. Therefore, about (50-90) full length hair strands should be collected from the scalp to use as a sample.
The fluoride ion (F-) is smaller in size than the oxide ion (O2-).
The ion with a smaller size is F- (fluoride ion) compared to O2- (oxide ion).
The size of an ion depends on the number of protons and electrons it has. Fluoride ion has one less electron than the oxide ion, making it smaller in size.
This trend can be explained by the concept of effective nuclear charge, where the positive charge of the nucleus is partially shielded by other electrons in the atom. As the atomic number increases from oxygen to fluorine, the increase in nuclear charge outweighs the additional electron-electron repulsions, resulting in a smaller size for fluoride ion.
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a 4he
b Na 2+
c Ca
d Mg
Na2+(answer B) represent ions.
This is because it has a charge of 2+. ion is formed when an atom gain or lose electrons. when an atom lose electrons it form ion which is positively charged . On the other hand when atom gain electrons it forms ion of negatively charged. Na2+ has a charge of 2+ since it loses two electrons.